Rotary piston machine

ABSTRACT

A rotary piston device in which two pistons are mounted in an annular chamber for unidirectional movement therein while moving relatively to each other. Radial elements connected to the piston are journaled on a common axis coinciding with the central axis of the annular chamber and a control member eccentric to the axis nonrotatively but radially slidably engages the radial elements and thereby effects positive control of the relative movement of the pistons during unidirectional movement thereof in the chamber. Fluid passages provide for the supply and removal of fluid from between the opposed ends of the pistons.

[4 1 Oct. 23, 1973 ROTARY PISTON MACHINE Erich Klesatschke, Goethestrasse 4, Gerabronn, Germany Filed: July 16, 1970 Appl. No.: 55,342

Inventor:

[52] US. Cl. 418/37, 418/138, 418/144, 418/186 [51] Int. Cl. F01c l/00, F04c 1/00, F04c 17/00 [58] Field of Search 418/33, 35-37, 418/112,l16,138,144,l83,186;123/8.47

[56] References Cited UNITED STATES PATENTS 2,156,180 4/1939 Homer 418/33 3,572,985 3/1971 Runge... 418/138 1,328,410 1/1920 Weed 418/35 7 728,536 5/1903 Breed et a1. 418/35 3,227,090 1/1966 Bartolozzi 418/35 679,105 7/1901 Buck 418/116 1,048,844 12/1912 Madero 418/186 2,971,500 2/1961 Bancroft 418/37 3,556,694 1/1971 Bancroft 418/37 1,196,028 8/1916 Roseman-Rozewski 418/35 FOREIGN PATENTS OR APPLICATIONS 134,869 11/1919 Great Britain l23/8.47 187,818 ll/l922 Great Britain 418/37 28,318 8/1910 Great Britain..... 418/35 541,344 5/1922 France 418/37 Primary ExaminerCarlton R. Croyle Assistant Examiner.1ohn J. Vrablik AttorneyWalter Becker [57] ABSTRACT A rotary piston device in which two pistons are mounted in an annular chamber for unidirectional movement therein while moving relatively to each other. Radial elements connected to the piston are journaled on a common axis coinciding with the central axis of the annular chamber and a control member eccentric to the axis nonrotatively but radially slidably engages the radial elements and thereby effects positive control of the relative movement of the pistons during unidirectional movement thereof in the chamber. Fluid passages provide for the supply and removal of fluid from between the opposed ends of the pistons.

cram, 11 515mg i i ui s ROTARY PISTON MACHINE The present invention relates to a rotary piston machine, and it is an object of the present invention to provide an improved rotary piston machine in which the sealing problem can be controlled in a simple and reliable manner while the elements of the rotary piston machine can be produced by customary machining operations without difficulties.

This object and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIG. 1 diagrammatically illustrates an open rotary piston machine according to the invention which, in this particular in-stance, represents a compressor.

FIG. 2 is a section taken along the line II-II of FIG. 1.

FIGS. 3-8 respectively diagrammatically illustrate different positions of operation of the rotary piston machine according to FIGS. 1 and 2.

FIG. 9 illustrates a further embodiment of a rotary piston machine according to the invention which differs in construction from that of FIGS. 1 and 2 merely in the arrangement of the control openings and in the sealing limits provided in the pistons.

FIG. 10 represents a section taken along the line X-X of FIG. 9.

FIG. 11 diagrammatically illustrates a rotary piston machine which corresponds in principle to the design of FIGS. 9 and 10, and in which the pistons are provided with passages extending in the longitudinal direction of said pistons.

The rotary piston machine according to the present invention is characterized by pistons which rotate in the same direction in an annular chamber and also move relative to each other, said pistons being automatically guided by elements which are coaxially journalled within the annular chamber and which are rotatable relative to each other. The said elements are radially displaceably connected to a control member which is eccentrically located with regard to the guiding elements. A rotary piston machine of this type which, particularly when designed as'compressor, is of an especially simple overall structure is composed primarily of elements adapted to be machined on a lathe or the like andmakes possible over heretofore customary sealing elements the formation of the required sealing limits.

A particularly advantageous structure is obtained when the guiding elements and the control member are journallcd radially within the annular chamber and when the guiding elements are arranged coaxially with regard to the annular chamber. In this way a compact and nevertheless simple overall structure of the machine can be realized. In this repsect it is also particularly advantageous to arrange the guiding elements on the machine shaft which is coaxially arranged with regard to the annular chamber and to connect one of the guiding elements which are connected through the control member on the said shaft so as to be non-rotatable relative thereto. Such an arrangement yields a particularly simple power transfer.

When reversing this construction, it is also possible to journal the guiding elements on a shaft coaxial to the annular chamber and to design the control member which connects the guiding elements as machine shaft. Also with this embodiment, the individual machine elements can still be very favorably journallcd in the machine housing, and occurring forces can well be absorbed or controlled. For the intended simplified construction according to the invention it is particularly advantageous to design the control member as an annular body which is journalled radially inwardly of the annular chamber in the machine housing.

The desired guiding and control of the pistons can be realized according to the invention in a simple manner by providing each of the guiding elements with an arm which through the intervention of a pertaining bushing is mounted on the machine shaft while the guiding elements through the intervention of rotatable annular parts coaxially arranged with regard to the annular chamber are connected with the pertaining piston. In view of the connection of the pistons and the guiding elements through annular parts, it is possible by simple means to solve the problem of tightly sealing the annular chamber in which the pistons rotate in spite of the necessary connection to the guiding elements. A particularly simple solution of the problem, on one hand, to guide and support the pistons and, on the other hand, to maintain the annular chamber sealed which forms the working chamber, has been realized according to the invention by the fact that the annular parts in the radial inner range of the annular chamber respectively form a wallportion thereof and are sealingly rotatably interconnected while being movable relative to each other and while sealingly engaging the wall of the annular chamber.

In view of the manufacturing as well as the sealing problems, it is advantageous within the frame work of the present invention if the annular chamber has a circular cross-section and is defined by two annular semicups which are symmetrical with regard to the transverse central plane of the machine. The inner annular edges of these cups are radially set back and define an annular gap in which the annular parts are inserted.

If, in conformity with a further development of the invention, the annular parts have an angular crosssection and are so arranged that their respective radially outwardly extending leg is located in the annular gap and that the respective axially extending leg extends behind an axially extending guiding surface of the annular semi-cup, it is possible through the intervention of the annular parts to convey to the machine housing also the centrifugal forces which during the operation of the machine act upon the pistons so that the said pistons by the centrifugal forces cannot be pressed radially outwardly against the wall of the annular chamber. With such a support of the pistons through the annular parts, the pistons can also be guided in the annular chamber in a contact-free manner with the result that optimum working conditions are assured for the sealing elements. Pin connections, hooks, or the like, may be used for a supporting connection of the pistons with the respective pertaining annular part, said connecting preferably being a positive one.

For purposes of a simple design and a simple assembly, it is advantageous within the frame work of the present invention to brace the annular semi-cups, which substantially define the annular chamber, over their radial inner range in axial direction by lateral housing covers. These covers are from the outside supported by the annular collars of the annular semi-cups and are centered relative to the annular collars by a flange or the like. A particularly simple control of the guiding elements by the control part within the frame work of the present invention can be realized by designing the control part as a bushing. The bushing preferably has recesses through which the arm-shaped parts of the guiding elements extend, said arm-shaped parts being displaceable in the direction of their longitudinal extension and being mounted so as to be able to vary the angle thereof.

According to a further embodiment of the invention, which is particularly advantageous with regard to a quiet operation and a simple construction, the machine may be designed as compressor with two pistons which are curved in conformity with the annular chamber and which rotate in the same direction and are movable relative to each other. The connecting line which connects the centers of the pivotal guiding means for the two guiding elements associated with the pistons extends through the central axis of the control part.

The seal between the annular parts and the annular collars of the annular semi-cups may, in conformity with the invention, further be improved by chamfering the annular edge of the annular collar within its radial inner range, preferably at an angle of 45. In the annular chamber formed in view of the chamfering of the annular edge of the collar, a sealing ring of triangular cross-section can be inserted.

According to a further development of the invention, volume variable working chambers may within the annular chamber be delimited by pistons which, in conformity with the radius of the annular chamber, are curved and at least have a sealing limit formed by sealing elements in the form of piston rings. In this way, a sealing limit in the vicinity of each of the end faces of a piston may be provided.

With such an arrangement of the sealing limits, a provision of the control openings for the machine is expedient according to which the annular part respectively circulating with the respective piston forms a control part for the pertaining control openings or gas changing passages of the machine which are provided in the annular collar of the machine and are formed by bores which are substantially parallel to the machine axis or machine shaft of the annular chamber. The said bores lead into annular edges which face each other and define the annular gap, said bores being adapted to be controlled by recesses which are provided in those sides of the legs of the annular parts which are adjacent the annular edges, said recesses being radially open toward the outside toward the annular chamber.

According to a further feature of the invention, the control openings may be provided in the circumference of the annular chamber and are controllable by the sealing elements. Such an arrangement of the control openings brings about a structurally particularly simple solution. With the above mentioned arrangement of the control openings, it is advantageous to provide each piston with a sealing limit formed by a sealing element, said sealing limit preferably being provided in the central piston range with regard to the longitudinal extension of the piston. The width of the control openings measured in the direction of rotation of the pistons advantageously corresponds to the width of the sealing elements provided on each of the pistons and forming a sealing limit and is preferably smaller than the sealing elements.

With such an arrangement of the sealing limit, the

piston is within the range between the sealing limit and at least one of its end faces at least partially with regard to its diameter offset relative to the diamter of the annular chamber to a greater extent in order to permit a proper intake and exhaust of the working medium.

Referring now to the drawings in detail, the rotary piston machine illustrated in FIGS. 1-8 and designed as compressor has an annular chamber 1 in which there are provided two pistons 2, 3 adapted to rotate in the same direction and movable with regard to each other. Each of these pistons 2, 3 illustrated in FIG. 1 in a dead center position and having a circular cross-section in conformity with the cross-section of the annular chamber l, is near each of its end faces provided with a sealing limitation or sealing boundary 4' which is formed by sealing elements 4 having the shape of piston rings. Within the region between the sealing boundaries 4, the piston body is reduced in diameter in order to avoid a direct contact between the pistons and the wall of the annular chamber 1. The design of the pistons at their off-set portion, therefore, depends primarily merely on the required stability inasmuch as, in view of the forces to be absorbed, as low a piston weight as possible is of great importance. The forced guiding of the pistons 2, 3 is realized by guiding elements 5 which, in the specific embodiment shown, are journalled on the machine shaft 6 coaxially with regard to the annular chamber 1. Each of the guiding elements 5 comprises an arm 7 which is adjacent to a bushing 8 on shaft 6. The guiding element 5 of the piston which comprises arm 7 and annular bushing 8, in this instance of the piston 2, is non-rotatably connected to shaft 6 as has been indicated in the embodiment shown by the key and groove connection 9. The other guiding element, in other words the guiding element associated with the piston 3, is rotatably mounted on shaft 6. The guiding elements 5 are, in conformity with the present invention, automatically guided by a control member 10 which preferably comprises an annular body, especially a bushing, which comprises recesses 11 for passing the arms 7 of the guiding element 5 therethrough. The control part 10 is eccentrically located with regard to shaft 6 which is evident in particular from FIG. 2. Due to the fact that one of the guiding elements is non-rotatably connected to shaft 6, and furthermore due to the fact that the guiding elements are with regard to each other fixedly positioned by the control part 10, it is possible, when using the machine as compressor, to convey through the shaft to each of the pistons the necessary driving torque. Inversely, when the machine is being used, for instance, as motor, it is possible from the pistons through the guiding elements to convey a corresponding force to the shaft. In contradistinction to the illustrated embodiment, when reversing the kinematics, it is, of course, also possible through the control part 10 to convey a torque to the guiding elements 5 or, when using the machine as driving machine, to derive such torque. Instead of shaft 6, there will in such an instance be provided a shaft on which the guiding elements are journalled.

The connection between the arms 7 of the guiding elements 5, which rotate together with the control part 10, and the pistons 2, 3 is effected by annular parts l2, 13. These annular parts l2, 13 are in the specific embodiment shown parallel and symmetrical to that transverse central plane of the machine which is perpendicular to the axis ofthe annular chamber 1. As will be evident from FIG. 2, the annular parts l2, 13 are angleshaped and have a radially outwardly extending leg 12a, 13a as well as an axially extending leg 12b, 13b. The radially outwardly extending legs 12a, 13a of the annular parts 12, 13 which are preferably closed in themselves, are located in an annular gap 14 of the annular chamber 1. The annular gap 14 of the annular chamber 1 is delimited by annular collars 15, 16 respectively associated with annular semi-cups 17, 18 which substantially form the annular chamber 1 and preferably are components thereof. Those annular edges 19 of the annular collars 15, 16 which face each other and substantially define the annular edges of the annular collars 15, 16 are at least within their radial inner region somewhat slanted, and a triangular sealing ring 20 is inserted into the substantially triangular chamber which is formed by the chamfer or inclination.

Between the radially outwardly extending legs 12a, 13a of the annular parts 12, 13 there is inserted a further sealing ring 21 which in the particular embodiment is rectangular and which is arranged in corresponding grooves of the annular parts 12, 13. This sealing ring 21 may simultaneously be used for centering the annular parts 12, 13. The annular semi-cups 17, 18 have guiding surfaces for the axially extending legs, which guiding surfaces are formed by the radially inner surfaces of the annular flanges 15, 16 provided on the annular semi-cups. These guiding surfaces are, according to the embodiment shown, parallel to the axis of the machine. If these guiding surfaces are inclined with regard to the annular gap 14 (not shown) to such an extent that the radial distance with respect to the machine axis increases toward the annular gap 14, it is possible with a corresponding inclination of the axially extending legs of the annular parts that, in view of the guiding forces and in particular in view of the mass forces of the pistons, an axial thrust occurs as a result of which the annular parts will during operation be pressed against each other. This may contribute to an improved seal.

Gas change passages 22, as diagrammatically shown in FlG.2, lead into the ranges of the annular edges 19 which ranges are covered, by the outwardly extending legs 12a, 13a of the annular parts 12, 13. The passages 22 extend through the annular collars 15, 16 of which in the embodiment shown only the outer passages are indicated. Since the annular parts 12, 13 rotate together with the pistons, the gas change passages 22 or the control openings of the recesses 23 arranged accordingly in the annular parts and open toward the annular chamber 1 may be controlled. Thus, with the embodiment of a compressor according to the present invention, special control elements are not necessary.

The recesses 23 may thus advantageously, with respect to the pistons 2, 3 connected to the annular parts 12, 13, be arranged within the region of said pistons in the circumferential rearward end face.

In order to assure a good guiding of the piston by the respective annular part, it may be expedient to provide the piston which has a circular cross-section with a flat engaging surface for the annular part so that a good bracing of the piston against the annular part will be possible. in order further also within the range of the annular parts to assure a good seal through the sealing boundaries 4', it may be expedient so to arrange the piston rings 4 that they are substantially non-rotatable with regard to the piston. This can be realized by arranging the piston rings together with their respective separating groove in the region of the annular parts and in this region which overlaps with the annular parts flattening the piston rings on the outside. This flat portion may correspond substantially to the flat portion of the piston in the same region.

The arms 7 of the guiding elements 5 extend into the axially extending legs 12b and 13b of the annular parts 12, 13 as shown in FIG. 2 for the annular part 12 only. These arms are pivotable and are displaceable in radial direction while simultaneously being guided in the control part 10. This is realized in the embodiment by a ball joint 24. The supporting connection of the pistons 2, 3 with the annular parts 12, 13 is, as diagrammatically shown in FIG. 1, effected by means of pin connections 25 the pins 26 of which, on one hand, engage the radially outwardly extending legs 12a, 13a of the annular parts l2, l3 and, on the other hand, engage the body of the pistons 2, 3.

For purposes of arresting and centering the annular semi-cups l7, l8 and for journalling the control part 10 and shaft 6, housing covers 27, 28 are provided which through centering collars 29, 30 are positioned relative to the annular collars 15, 16 and rest on the same. The housing covers 27, 28 have central recesses 31, 32 in which the bearings 33 for the shaft 6 are arranged. The bearings are selected in the form of taper bearings so that by means of the shaft, the housing covers 27, 28 are adapted also axially to be braced with regard to each other. The recesses 31, 32 are adapted to be closed toward the outside through additional covers 34. Within the housing covers 27, 28 there are provided rccesses 35, 36 of a circular cross-section in which recesses there is guided the control part 10 which is in the form of a bushing. Aside from the bracing through the intervention of the housing covers 27, 28, the annular semi-cups are radially outwardly flanged.

As will be seen from FIG. 1 in connection with FIG. 2, the connecting lines of the centers 37 of the ball joints 24, in other words the guiding means for the arms 7 of the guiding elements 5 in the control member 10, are in the specific embodiment shown so located that they intersect the axis 38 of the control member 10. This arrangement brings about that the guidline elements 5 after each rotation of the shaft by always occupy the same position so that for a complete revolution of the shaft two complete and equal working cycles are obtained. With such a design of the control machines for the pistons, the pistons will in the vertical position of said connecting line occupy a dead center position with regard to the line connecting the axis of rotation 38 of the control member 10 with the axis of the machine shaft. Different working positions of the machine and their operationare evident from FlGS.'3-8 which will be discussed in detail further below. FIG. 1 also shows that for purposes of cooling the housing range inwhich the direction of rotation indicated in FIGS. 2-8 always the compression occurs, it is possible through this housing range to drawn-in, for instance, air. To this end, the housing is in the direction of rotation and over the compression range provided with a passage 40 through which cold air is drawn in. in this way, it is possible also with thermally maximum loads on the machines to avoid distortions of the housing. Aside therefrom (only indicated in the drawing), the outer circumference of the annular semi-cups 17, 18 is provided with such a great number of cooling fins which simultaneously stiffen the cups that without the above described additional features a sufficient cooling of the machine will be assured even under unfavorable circumstances.

Since, as FIGS. 4 to 8 show, the compression is effected over a major portion of the circumference, namely practically over 180, the respectively intended degree of compression can in a simple manner with a gas supply according to FIGS. 1 and 2 be limited by providing the gas change passages, in this instance the connecting passages, already at a greater distance ahead of the dead center point or only starting near said dead center point. If the gas change passages are arranged near the dead center point, high degrees of compression are obtained. If, however, the opening occurs at an earlier time, corresponding lower degrees of compression are obtained in which instance it is, of course, necessary that the delivery occurs against a corresponding resistance, in other words for instance against a pressure limiting valve or against an air chamher.

As will be seen from the drawings, the machine is equally suitable to be employed as internal combustion engine in which instance, in differentiation to the illustration, obvious changes have to be effected. The machine may also be employed as pump or vacuum pump while its main construction remains the same.

Referring now to FIGS. 3-8, it will be noted that FIG. 3 shows a starting position corresponding to the showing of FIG. I. From this starting position, the working chamber V will successively up to the upper dead center point position of FIG. 7 decrease, said working chamber being defined by pistons 2 and 3. FIGS. 4, 5 and 6 illustrate how in the intermediate phases the working chamber S continuously increases until it has reached its maximum size in FIG. 7. According to the illustration of FIG. 5, the working chambers S and V are of the same size. In conformity with the indicated direction of rotation, the working chamber S represents the suction chamber and the working chamber V represents the compression chamber. The displacement of the pistons relative to each other during the same direction of rotation is due to the different angular positions of the guiding elements 5 with regard to the control member during the simultaneous change in the radius, i. e., the distance between the center point 37 of the guiding means formed by the ball joint 24 on one hand and the axis of the shaft on the other hand.

FIGS. 9 and 10 illustrate a rotary piston machine which, as far as structure is concerned, substantially corresponds to the structure of FIGS. 1 and 2. Therefore, corresponding parts have been designated with the same reference numeral. Also the operation of the machine of FIGS. 9 and 10 corresponds substantially to that of FIGS. 1 and 2 so that the remarks set forth in connection with FIGS. 3-8 also apply to the machine of FIGS. 9 and 10. Therefore, only the differences between FIGS. 9 and 10 on one hand and FIGS. 1 and 2 on the other hand will now be described.

The working chambers formed by the pistons are according to FIGS. 9 and 10 separated from each other by a sealing boundary 54 which latter is formed by two piston rings 54 which are spaced from each other by a relatively small distance. The piston rings 54 are, according to FIGS. 9 and 10, provided preferably in the intermediate range of the longitudinally extending piston which is curved in conformity with the annular shape of the annular chamber 1. With such a design ac cording to the invention, the piston may again over its entire length have a reduced diameter relative to the diameter of the annular chamber so that a direct contact between the piston and the wall of the annular chamber will be assured.

The inlet and outlet passages 22a and 22b of the machine are controlled by the sealing boundaries 54, said passages 22a and 22b leading directly into the annular chamber 1 and forming control openings 23. Since the sealing boundaries 54' of this embodiment are with regard to the length of the piston provided in the intermediate range of said piston, it will be possible through the distance between the wall of the piston and the wall of the annular chamber to control the feeding and discharge of the working medium to and from the passages 22a, 22b respectively. Thus, for instance, when employing the machine as liquid pump, the said feeding and discharge can be facilitated by offsetting the piston as to its diameter not only with regard to said annular chamber, which is desired for reducing the friction, but as shown in FIG. 11 by providing in pistons 2 and 3 toward the sealing boundaries 54' at least from one piston end face a passage 55 which is formed, for instance, by a bulge of the piston. The passage is expediently arranged in a region of the piston which during the rotation of the piston will come into alignment with the control openings 23. In order to avoid overlapping and thereby losses in power, it will be expedient, as evident from the drawing, if the width of the control openings 23 measured in the direction of rotation of the pistons 2, 3 is less than the width of a sealing boundary 54'.

Whereas in the illustrated embodiment in which the pistons 2, 3 have at their compression side reached their maximum mutual approach, the sealing boundaries 54 and the control openings 23 are located in the same radial planes (which is a preferred embodiment), it is also possible within the scope of the invention so to arrange the control openings 23 with regard to said piston position that merely one of said openings will at this piston position be covered by a sealing boundary 54.

As mentioned above and shown in FIG. 11, it may be expedient, particularly when employing the machine as liquid pump, starting from the end faces of the pistons 2, 3 and extending into the range of the sealing boundaries 54', to provide passages 55 which are located in the overlapping range of the control openings 23' in order to be able to control the exchange of working medium in a suitable manner. In order to be able to realize this while taking into consideration the different conditions with regard to discharge and inlet, it may be advantageous to offset with regard to each other the inlet passage 22a and the outlet passage 22b relative to a transverse central plane of the machine and to associate with the inlet and outlet passages feeding passages in the piston in conformity with the specific requirements.

Especially with the design of FIGS. 9 and 10, in other words with control passages 22a and 22b in the wall of the annular chamber, the machine may without changes be employed for various purposes, such as a pump and compressor and, therefore, is very suitable for employment in emergencies. This flexibility of employment is also aided by the fact that also with this embodiment there may also be provided a great number of preferably radial cooling fins which will even under extreme conditions assure a sufficient cooling of the machine. With corresponding changes, the rotary piston machine according to the invention and FlGS. 9 and 10 in particular is, of course, also adapted to be employed as motor.

It is, of course, to be understood that the present invention is, by no means, limited to the particular showing in the drawings but also comprises any modifications within the scope of the appended claims.

What is claimed is:

1. In a rotary piston machine: an annular chamber, a pair of curved segment-shaped pistons mounted in said chamber and adapted for unidirectional movement therein, power transmitting means connected to each piston and each including a radial guiding element extending toward the central axis of said annular chamber, means journalling said radial guiding elements for rotation about a predetermined axis as the respective pistons move unidirectionally in said chamber and for rotation relative to each other as the said pistons move relatively, and a control member rotatable on an axis parallel to and displaced radially from the axis on which said radial elements are journalled, said control member nonrotatively but radially displaceably engaging said radial guiding elements whereby said pistons move relative to each other in the circumferential direction of said chamber in a predetermined controlled manner as the pistons move unidirectionally in said chambensaid radial guiding elements and said control member being disposed radially inwardly of said annular chamber and the axis on which said radial guiding elements are journalled being the central axis of said chamber, said means journalling said radial guiding elements being a shaft coaxial with the central axis of said annular chamber, means for effecting a power transmitting connection to said control member, which includes a housing forming said annular chamber, said control member being rotatably journalled in said housing, a bushing slidable on each radial element and connected to said control member, and an annular member coaxial with the central axis of said annular chamber for each piston, each piston being connected to a respective annular member and each annular member being connected to a respective radial element, said annular chamber including an annular gap at the radially inner side, said annular members being disposed in side by side relation in said gap and sealed to each other and to the sidewalls of said gap, said chamber being formed by a pair of housing members each having an annular cavity therein and secured together in face to face engagement with said cavitiesin registration to form said chamber, said chamber being circular in cross section, said housing members being spaced at the radially inner side of said chamber to form said gap, each housing member having an inwardly facing axial surface adjacent said gap, each said annular member having an axial leg engaging a respective said axial surface and a radial leg extending into said gap, including pin-like members positively connecting each piston to the respective annular member, said chamber being formed by a pair of annular housing members which are cup-like in cross section and secured together in face to face relation, each housing member having a cylindrical surface on the radially inner side and radial surfaces on the axially outer sides adjacent the respective said cylindrical surface, and centering cover members having radial portions engaging said radial surfaces and axial portions engaging said cylindrical surfaces, said control member being in the form of a sleeve, and circumferentially spaced aper tures in said sleeve through which said radial elements slidably extend, each housing member being bevelled off at the corner adjacent the juncture of the radial and axial legs of the respective annular member, and an annular seal element of triangular cross section disposed in the space provided by each bevelled off portion of said housing members.

2. In a rotary piston machine: an annular chamber, a pair of curved segment-shaped pistons mounted in said chamber and adapted for unidirectional movement therein, power transmitting means connected to each piston and each including a radial guiding element extending toward the central axis of said annular chamber, means journalling said radial guiding elements for rotation about a predetermined axis as the respective pistons move unidirectionally in said chamber and for rotation relative to each other as the said pistons move relatively, and a control member rotatable on an axis parallel to and displaced radially from the axis on which said radial elements are journalled, said control member nonrotatively but radially displaceably engaging said radial guiding elements whereby said pistons move relative to each other in the circumferential direction of said chamber in a predetermined controlled manner as the pistons move unidirectionally in said chamber, said radial guiding elements and said control member being disposed radially inwardly of said annular chamber and the axis on which said radial guiding elements are journalled being the central axis of said chamber, said meansjournalling said radial guiding elements being a shaft coaxial with the central axis of said annular chamber, one of said radial guiding elements being rotatable on said shaft and the other of said radial elements being keyed to said shaft, a housing forming said annular chamber, said control member being rotatably journalled in said housing, a bushing slidable on each radial element and connected to said control member, and an annular member coaxial with the central axis of said annular chamber for each piston, each piston being connected to a respective annular member and each annular member being connected to a respective radial element, said annular chamber including an annular gap at the radially inner side, said annular members being disposed in side by side relation in said gap and sealed to each other and to the side walls of said gap, said chamber being formed by a pair of housing members each having an annular cavity therein and secured together in face to face engagement with said cavities in registration to form said chamber, said chamber being circular in cross section, said housing members being spaced at the radially inner side of said chamber to form said gap, each housing member having an inwardly facing axial surface adjacent said gap, each said annular member having an axial leg engaging a respective said axial surface and a radial leg extending into said gap, pin-like members positively connecting each piston to the respective annular member, said chamber being formed by a pair of annular housing members which are cup-like in cross section and secured together in face to face relation, each housing member having a cylindrical surface on the radially inner side and radial surfaces on the axially outer sides adjacent the respective said cylindrical surface, and

centering cover members having radial portions engaging said radial surfaces and axial portions engaging said cylindrical surfaces, said control member being in the form of a sleeve, and circumferentially spaced apertures in said sleeve through which said radial elements slidably extend, each housing member being bevelled off at the corner adjacent the juncture of the radial and axial legs of the respective annular member, and an annular seal element of triangular cross section disposed in the space provided by each bevelled off portion of said housing members.

3. A rotary piston machine according to claim 2 which includes port means in said annular chamber, each piston having a sealing means thereon controlling said port means, said sealing means being mounted on said pistons near the longitudinal centers thereof, the

said sealing means thereon. 

1. In a rotary piston machine: an annular chamber, a pair of curved segment-shaped pistons mounted in said chamber and adapted for unidirectional movement therein, power transmitting means connected to each piston and each including a radial guiding element extending toward the central axis of said annular chamber, means journalling said radial guiding elements for rotation about a predetermined axis as the respective pistons move unidirectionally in said chamber and for rotation relative to each other as the said pistons move relatively, and a control member rotatable on an axis parallel to and displaced radially from the axis on which said radial elements are journalled, said control member nonrotatively but radially displaceably engaging said radial guiding elements whereby said pistons move relative to each other in the circumferential direction of said chamber in a predetermined controlled manner as the pistons move unidirectionally in said chamber, said radial guiding elements and said control member being disposed radially inwardly of said annular chamber and the axis on which said radial guiding elements are journalled being the central axis of said chamber, said means journalling said radial guiding elements being a shaft coaxial with the central axis of said annular chamber, means for effecting a power transmitting connection to said control member, which includes a housing forming said annular chamber, said control member being rotatably journalled in said housing, a bushing slidable on each radial element and connected to said control member, and an annular member coaxial with the central axis of said annular chamber for each piston, each piston being connected to a respective annular member and each annular member being connected to a respective radial element, said annular chamber including an annular gap at the radially inner side, said annular members being disposed in side by side relation in said gap and sealed to each other and to the side walls of said gap, said chamber being formed by a pair of housing members each having an annular cavity therein and secured together in face to face engagement with said cavities in registration to form said chamber, said chamber being circular in cross section, said housing members being spaced at the radially inner side of said chamber to form said gap, each housing member having an inwardly facing axial surface adjacent said gap, each said annular member having an axial leg engaging a respective said axial surface and a radial leg extending into said gap, including pin-like members positively connecting each piston to the respective annular member, said chamber being formed by a pair of annular housing members which are cup-like in cross section and secured together in face to face relation, each housing member having a cylindrical surface on the radially inner side and radial surfaces on the axially outer sides adjacent the respective said cylindrical surface, and centering cover members having radial portions engaging said radial surfaces and axial portions engaging said cylindrical surfaces, said control member being in the form of a sleeve, and circumferentially spaced apertures in said sleeve through which said radial elements slidably extend, each housing member being bevelled off at the corner adjacent the juncture of the radial and axial legs of the respective annular member, and an annular seal element of triangular cross section disposed in the space provided by each bevelled off portion of said housing members.
 2. In a rotary piston machine: an annular chamber, a pair of curved segment-shaped pistons mounted in said chamber and adapted for unidirectional movement therein, power transmitting means connected to each piston and each including a radial guiding element extending toward the central axis of said annular chamber, means journalling said radial guiding elements for rotation about a predetermined axis as the respective pistons move unidirectionally in said chamber and for rotation relative to each other as the said pistons move relatively, and a control member rotatable on an axis parallel to and displaced radially from the axis on which said radial elements are journalled, said control member nonrotatively but radially displaceably engaging said radial guiding elements whereby said pistons move relative to each other in the circumferential direction of said chamber in a predetermined controlled manner as the pistons move unidirectionally in said chamber, said radial guiding elements and said control member being disposed radially inwardly of said annular chamber and the axis on which said radial guiding elements are journalled being the central axis of said chamber, said means journalling said radial guiding elements being a shaft coaxial with the central axis of said annular chamber, one of said radial guiding elements being rotatable on said shaft and the other of said radial elements being keyed to said shaft, a housing forming said annular chamber, said control member being rotatably journalled in said housing, a bushing slidable on each radial element and connected to said control member, and an annular member coaxial with the central axis of said annular chamber for each piston, each piston being connected to a respective annular member and each annular member being connected to a respective radial element, said annular chamber including an annular gap at the radially inner side, said annular members being disposed in side by side relation in said gap and sealed to each other and to the side walls of said gap, said chamber being formed by a pair of housing members each having an annular cavity therein and secured together in face to face engagement with said cavities in registration to form said chamber, said chamber being cIrcular in cross section, said housing members being spaced at the radially inner side of said chamber to form said gap, each housing member having an inwardly facing axial surface adjacent said gap, each said annular member having an axial leg engaging a respective said axial surface and a radial leg extending into said gap, pin-like members positively connecting each piston to the respective annular member, said chamber being formed by a pair of annular housing members which are cup-like in cross section and secured together in face to face relation, each housing member having a cylindrical surface on the radially inner side and radial surfaces on the axially outer sides adjacent the respective said cylindrical surface, and centering cover members having radial portions engaging said radial surfaces and axial portions engaging said cylindrical surfaces, said control member being in the form of a sleeve, and circumferentially spaced apertures in said sleeve through which said radial elements slidably extend, each housing member being bevelled off at the corner adjacent the juncture of the radial and axial legs of the respective annular member, and an annular seal element of triangular cross section disposed in the space provided by each bevelled off portion of said housing members.
 3. A rotary piston machine according to claim 2 which includes port means in said annular chamber, each piston having a sealing means thereon controlling said port means, said sealing means being mounted on said pistons near the longitudinal centers thereof, the extent of each said port means in the circumferential direction of said chamber being not greater than the extent of said sealing means in the same direction, each piston being turned in the circumferential direction of said chamber, sealing means on each piston sealingly engaging the chamber, each piston along the length thereof not supporting said sealing means being radially spaced from said chamber, and each piston having groove means formed therein extending longitudinally thereof from at least one end of the piston toward the said sealing means thereon. 